Eoin MACNEILL (1867-1945) was the first academic historian of early medieval Ireland; he is frequently considered to be the founder of the discipline of early Irish history. He was also a prominent nationalist activist, a revolutionary, and a minister in the first Irish Free State government. This paper will consider the shared inspirations for MACNEILL the politician and MACNEILL the scholar. In particular, it will focus on MACNEILL’s belief that the medieval past of Ireland was the making of its national character and the foundation of its right to independence from the British Empire. This brought him into conflict with the great unionist historian of Norman Ireland, Goddard Henry ORPEN. Their debate, revolving around contested pasts, proved to be troublesome for later generations of historians who were concerned to write an Irish history free of political bias. But MACNEILL was no mere propagandist. He was passionately devoted to the writing of source-driven history, one reliant upon core research skills in language and palaeography. He believed history should be scientific but not necessarily, or even ideally, value-free. This paper will examine these issues, primarily through the lens of MACNEILL’s career up to the formation of the Irish Free State (1922) and subsequent Civil War (1922-1923). It will show the extent to which his disagreements with ORPEN, as well as MACNEILL’s efforts to accurately delineate the early Irish past for scholars and, crucially, the wider public, were tied to his conviction that understanding the medieval was always relevant for contemporary societies.